Commenting out the InfluxDB block in Home Assistant does not stop the writes

Home Assistant's InfluxDB integration can live in a UI config entry instead of configuration.yaml. Before moving or retiring the database, find the real writers in its own log.

I was about to move an InfluxDB 2 instance into the cluster. The ticket said Home Assistant wrote to it continuously, but the influxdb: block in Home Assistant’s configuration.yaml was commented out. So who was writing?

The YAML block isn’t the only place

The InfluxDB integration can also be set up in the UI, and then it lives in /config/.storage/core.config_entries with the domain influxdb and the URL of the server. The YAML can be commented out while that entry keeps working. I found it by reading that file with a short script that skipped the token and password fields.

Trust the server’s log, not the config

The firm answer came from InfluxDB. I counted the callers in its log:

docker logs --since 24h influxdb | grep -o remote=

Over 24 hours there were 19,297 POST /api/v2/write, all from the address of Home Assistant, and a handful of HEAD requests from a dashboard’s uptime check. Nothing else wrote.

The command took about five minutes, because debug logging was on and the log was huge. A fresh instance of mine runs at the default level, so next time it’s quicker. That’s worth knowing before you plan to migrate a database whose writers you haven’t proven.